Method of making helical expansible reamers



April 7, 1925.

. N. A. :BHATTO METHOD OF MAKING HELICAL EXPANSISLE BEAMERS Filed Dec; 9 1923 c in ucuhw teale350 V l ll it is dwailfil.

VJJV'TEB A. SEATTO. U3? MILLEESBUELG, PEENSYLVAIM.

EETHGLD MAKING YELZ-JAL EXEANSIIBLE Application tiled December 2%, H23. Serial 1W0. $83,524.

To all whom it may concern:

Be it known that l, Names A. SHArro, a citizen of the United States, residing at lriillersburg, in the county or" Dauphin and State of Pennsylvania, have invented certain new and useful Improvements in Methods of Making Helical Expansible Boomers; and I do hereby declare the following to be a. full, clear, and exact description of the invention, such as will an able others, skilled in the art to which it appcrtains to make and use the same.

This invention relates to a method of making a helical cxpansible rcanier from solid stock, the object being to obtain or provide an cxpansiblc reemer having as great or greater helical angle of its flutes as is obtainable in non-expansible reemers.

.lt is well known in the art that reamers having helical flutes function much more etlii-icntly than reainei's with straight flutes, but prior to my invention it has not been possible to make an expansible reamer having" flutes of as great helical angle as can be provided in solid or non-expansible leaniers.

Une of the reasons, it not the main reason, which has made it impossible to make an cxpansible reamer of as great helical angle of its flutes as in solid rcaniers is that it has not been possible to cut slots between the flutes of as great helical angle as the flutes. The slots are cut by a saw, and due to the fact that the diameter of the saw must be such that it can be suitably held on its arbor and also of such diameter as to enable the proper depth of slot to be cut, the saw becomes of such diameter as to prevent cutting of a lielicalslot oi any greatangle. If too great a helical slot is attempted to be cut, the saw will bind in the slotand buckle up and break.

Referring to the accompanying drawings, Fig. 1 is a sectional viewshowing the stock from which the reamer is to be made, the stock having been bored with bores of two different diameters and threaded at one end.

Fig. 2 is a plan view of the partially cornpleted reanier, the same having been liuted.

Fig. 3 is a view similar to Fig. 2 showing the slots between certain of the flutes of the reamer.

Fig". l is a view similar to Fig. 3 showing the filling strips as having been inserted in the slots.

Fig. 5 shows the reamer as having been twisted, the filling strips remaining in piece.

Fig. 6 is a cross-sectional view on line 6-6 of Fig. 5, the filling strips having been removed from the slots; and

Fig. 7 is a view of the expander element.

The helicalexpansible reamer made in accordance with my invention is of the having flutes 1 reumer body 2, that is to say, the flutes terminute short of the ends "of the reamer. 'lhe reamer has a central bore 3 extending from one end the far end of the flutes. The open end of the bore is threaded to receive it screw 4 whii-h has a pointed end 5 adapted to engage a conical seat 6 within the bore interr intermediate the ends of t e thereof to a point adjacent,

mediate the ends of the flutes to expand the latter as may be required. T he conical seat is formed by enlarging the bore fromits.

open end to said seat. This manner of obtaining expansion of the reamer is well known in the art and is ent invention;

According to the invention, I first with accntral bore 7 of uniform diameter, the bore extending from one end of the preferred method of my provide the reamer body-' no pert of the presroamer to a point somewhat in advance or" the point where the flutes 1 will be; The flutes are milled in the usual manner and are preferably milled straight. At this point, it may be stated that it is whether or not the flutes are first provided. or whether the bore is first; provided. After the flutes have been rality of slots 8 are cut by means'of a saw between the flutes, the slots pansion of the reamer, but more than three slots may be provided if desirable. It will be understood that the number of flutes may be in excess of the number of slots, and consequently two or more flutes may be included on the segment between said slots. The number of flutes provided will'depend on the diameter of the reamer and will conform to approved reamerdesign.

l have stated that the flutes and slots should be milled straight; This is"primerily for the reason that a straight-flute a reamer reamer is more cheaply made then optional provided, a pin-,-

extending par- 1 allel with the flutes and through the shell having helical flutes; and furthermore, no trouble will then be experienced in cutting the slots.

In order to obtain the desired twist or helical angle of the flutes, I place filler strips 9 in the slots and heat the reamer sufficiently to enable the same to be twisted in the fluted and slotted part, which as already stated, is intermediate the ends of 10 the reamer; Twisting of the reamer is preferably accomplished by placing the same between two members adapted togrip the terminal ends thereof and then turning one of said-gripping members sufliciently to impart the desired degree of twist orhelical angle to the flute. The filling strips in the slots. are then removed and the reamer further bored to provide the large bore 3 and the internal threads 10 at one end of l the reamer and then treated and finished in the usual manner; that is to say, by tempering and grinding. I. is found necessary-to provide filling strips in the slots to prevent the latter from closing up when the reamer is, twisted.

ing the making of the bore until after the reamer has been twisted. According to this modified form of the invention the reamer will be fluted and slotted in the manner already described, but inasmuch as the reamer body has not been provided with a central bore, the reamer segments between the slots will be connected to a central core, it being understood that the depth of the slot .is not suflicicnt to reach to the center 40 of the reamer. After the reamer has been fluted and slotted, the same is heated and twisted in the manner described above. Thereafter, the reamer is bored to remove the core, the here being of such diameter that the segments of the res er between the slots will be free from one another. The reamer is then finished in the imanner already described in connection wit the preferred method. It may be stated a. this point that filling strips need not be inserted in the slots when the core is left in the" reamer during the twisting operation. Thegintercohnection between the reamer segments by the core is s eh that the slots will not close up during the twisting o oration.

. It will now e seen that I have provided a simple and practical method for obtaining helical expansible reamers. As heretofore stated, it has not been possible prior to my invention. to provide a reamer having helical Lesasso flutes of eat angle, the reamer having a bore providing for the insertion of arreapandingelement. Reamers made according to the present invention meet a long-felt ing flutes and radial slots between and parallel with the flutes, placing filler strips in the slots, heating the reamer, and twisting the same to obtain the desired helical angle of the flutes.

3. The method of making an expansible reamer from solid stock which consists in providing a'central bore or uniform diameter in the reamer body, providing flutes and radial slots between and parallel with the slots, the slots extending through the shell formed by said here, placing filler strips in the slots, heating the reamer, and twisting the same to obtain the desired helical angle of the flutes. 3

4. The method of making anexpansible reamer from soiid stock which consists in providing-a central bore of uniform diameter in the reamer body, providin flutes and radial siots between and paraiiel with the slots, intermediate the ends ofthe said body, the slots extending through the shell formed by said bore, placing filler strips in the slots, heating the reamer, and twisting the same to obtain the desired helical angle of the flutes.

5. The method of making a reamer which consists in rovidin flutes and radial slots between an paralle with the flutes, heating the-reamer and twistin the same to obtain the desired helical angle of the flutes, and thereafter boring the reamer to free the segments between the slots. r

6. The method of making a reenter which consists in providing flutes and radial slots between and parallel with the flutes, intermediate the ends of the said body, heating the reamer and twisting the same to obtain the desired heiical angle of. the flutes, and thereafter borin the reamer to free the segments between t as slots.

In testimony whereof I aflix my signature.

EVALTER A. SHATIU.

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